This invention relates to miniature lamps and, in particular, to miniature lamps having an integral reflector, for example, for use in flashlights.
Flashlights conventionally employ an efficient, short focal length, parabolic reflector and a prefocused type of incandescent lamp. "Efficient" refers to the light control ability of the reflector; specifically, to reflectors in which the plane of the open end of the reflector is located outside the focus from the vertex of the parabola. "Prefocused" refers to a lamp having a base collar from which the filament is located within predetermined tolerances. Prefocused lamps are necessitated by the combinations of lamp parts tolerances and variations in filament positioning introduced by the lamp making process.
The prefocused lamp is secured to the reflector in a variety of ways, including screw caps, coil springs, and leaf springs. Electrical contact is made to the bottom contact of the lamp base from the center contact of the batteries and to the lamp base shell by way of the flashlight switch.
While providing more controlled light than available without prefocused lamps, flashlights of the prior art do not have very closely controlled optics depending as they do on the fit of the bulb within its socket. Also, the reflector tends to deteriorate with time, further reducing the efficiency of the flashlight. In general, it is desired to produce a more efficient system at a reasonable price.
While lamps with integral reflectors are known outside the flashlight art, e.g., U.S. Pat. No. 3,488,543, these lamps use an all-glass reflector and do not hold the lamp in place by a portion of the bulb. Rather, the seal area of the lamp is embedded in cement and the lamp must be held in position while the cement dries.